I personally see no reason for Mesa's Shield to be nerfed. Most of the time, it's the only thing keeping me alive while I use the Peacemaker.
As for other Frames to rework, my biggest suggestion would be a rework of Loki. His abilities are absurdly lackluster when compared to the other spy Warframes. I'd take Wukong into a spy mission over Loki. The fact that his abilities don't actually do any damage is just icing on the proverbial cake.
His Decoy is barely worth the energy cost. The Augment for it doesn't really improve it. Maybe it'll save your life once or twice, but Loki is at his best when he's invisible, so a good Loki player would never need to rely on it for an average mission.
His Switch-Teleport ability is just a crappier version of Ash's teleport, made worse since it doesn't kill the enemies targeted.
The only two good abilities he has are his Invisibility and his Disarm, and even those have problems. His Invisibility has more speed compared to Ivara, but her Augment to walk through lasers puts her on top. The Augment is basically a rip-off of Banshee's passive ability, but worse.
The Disarm is probably his most useful ability outside of stealth, simply because of the fact that it disarms enemies. But even then, the ability does nothing else except disarm and occasionally do Impact damage. The Augment allows it to do radiation damage, but making enemies attack each other isn't as effective if they don't have their primary weapons.
This is my idea for a rework:
Passive: Hushed: The Hushed Invisibility Augment is folded into his regular kit, with the amount of noise Loki makes depends on what rank the Loki Warframe is. Level 30 makes him completely silent to enemies even when not Invisible.
New First Ability: Wall Walk: Loki can walk on the walls and ceiling like they were the normal floor. His weapons get increased Critical Chance while he's attached. Duration based that drains energy while active. Can turn Invisible while attached at double energy cost.
Invisibility Changes: While Invisible, Loki has a 50% chance to Auto Hack consoles, and gains increased Stealth Damage. All Throwing Knife weapons do double damage, and he can carry more ammo for them. This includes the throwing mine weapons.
Switch Teleport Changes: Swapping with an enemy inflicts a Bleeding status effect on them. Charging the ability makes it so that, upon switching places, Loki leaves behind an explosive charge where you were standing. Loki can now target objects with the ability. The Safeguard Switch Augment is rolled into the main ability.
Radial Disarm Changes: In addition to disarming enemies, this ability receives the Chroma treatment, allowing it to do radial elemental damage based on the Warframe's energy color. The sub-elements of Blast, Corrosive, Radiation, Viral, Gas, and Magnetic are unlocked after the first Forma and are based on combining the two Energy Colors. Unlike Chroma or Lavos, you cannot switch the elements mid-mission.
These changes would, in my opinion, make Loki much better while keeping his status as an effective stealth Warframe.
Please share your opinions.